#' @name biplot
NULL

#' @noRd
#' @keywords Internal
.biplot <- 
    function(x,
             comp = c(1,2),
             block = NULL,
             ind.names = TRUE,
             group = NULL,
             cutoff = 0,
             col = NULL,
             ind.names.size = 3,
             ind.names.col = color.mixo(4),
             ind.names.repel = TRUE,
             pch = 19,
             pch.size = 2,
             var.names = TRUE,
             var.names.col = 'grey40',
             var.names.size = 4,
             var.names.angle = FALSE,
             var.arrow.col = 'grey40',
             var.arrow.size = 0.5,
             var.arrow.length = 0.2,
             ind.legend.title = NULL,
             vline = FALSE,
             hline = FALSE,
             legend = if (is.null(group)) FALSE else TRUE,
             legend.title = NULL,
             pch.legend.title = NULL,
             cex = 1.05,
             ...
    )
    {
    
        pch.levels <- pch

        # check for inappropriate args
        extra_args <- list(...)
        # check for deprecated args
        if ("col.per.group" %in% names(extra_args)) {
        warning("'col.per.group' is deprecated, please use 'col' to specify colours for each group")
        }
        if ("pch.levels" %in% names(extra_args)) {
            warning("'pch.levels' is deprecated, please use 'pch' to specify point types")
        }

        col.per.group <- col

        object <- x
        rm(x)
        ## for implicit support of non-pca objects - experimental
        block <- .change_if_null(block, 'X')
        comp <- .check_comp(comp, ncomp = object$ncomp)
        block <- match.arg(block, choices = names(object$variates))
        hide <- 'none'
        selection <- rowSums(object$loadings[[block]][, comp]) != 0 
        loadings <- object$loadings[[block]][selection, ]
        loadings <- data.frame(loadings)
        
        ## scale check
        if (isFALSE(object$call$scale))
            warning("The 'tune.spca' algorithm has used scale=FALSE. We recommend scaling the data",
                    " to improve orthogonality in the sparse components.")
        ## cutoff correlation
        cutoff <- .check.cutoff(cutoff)
        cors <- cor(object[[block]][, selection], object$variates[[block]][, comp], use = 'pairwise' )
        # cors <- apply(cors, 1, function(x) (sqrt(sum(x^2))))
        # above.cutoff <- cors >= cutoff
        above.cutoff <- apply(cors, 1, function(x) any(abs(x) >= cutoff))
        loadings <- loadings[above.cutoff,]
        
        variates <- object$variates[[block]]
        variates <- data.frame(variates)
        ## scaler of var vs sample coordinates
        scaler <- max(variates, na.rm = TRUE)/max(abs(loadings), na.rm = TRUE)
        
        PCs <- paste0('component_', comp)
        expl_vars <- round(object$prop_expl_var[[block]]*100)[comp]
        axes.titles <- sprintf("%s   (%s%%)", PCs, expl_vars)
        ind.names <- .get.character.vector(ind.names, vec = rownames(variates))
        
        variates$ind.names <- ind.names
        col.group <-
            .get.cols.and.group(
                col.per.group = col.per.group,
                group = group,
                col = col,
                object = object,
                n_ind = nrow(variates)
            )
        group <- col.group$group
        col.per.group <- col.group$col.per.group
        if (length(col.per.group) == 1)
        {
            legend <- FALSE
        }
        
        ## ------------- outline
        gg_biplot <- 
            ggplot() + 
            theme_classic() +  
            labs(x = axes.titles[1], 
                 y = axes.titles[2])
        ## vline and hline
        if (vline)
        {
            gg_biplot <- gg_biplot + geom_vline(xintercept = 0, size = 0.3, col = 'grey75')
        }
        if (hline)
        {
            gg_biplot <- gg_biplot +  geom_hline(yintercept = 0, size = 0.3, col = 'grey75')
        }
        
        
        ## ------------- inds
        if (! 'ind' %in% hide) 
        {
            if (!is.null(pch)) 
            {
                ## ------------- advanced user args
                fill <- ifelse(is.null(list(...)$fill), 'black', list(...)$fill)
                alpha <- ifelse(is.null(list(...)$alpha), 1, list(...)$alpha)
                
                pch.res <- .get.pch(pch, pch.levels, n_ind = nrow(variates))
                pch <- pch.res$pch
                pch.levels <- pch.res$pch.levels
                pch.legend <- pch.res$pch.legend
                
                ## get 'pch' and 'group' arg used for legends so we can handle
                ## legends whether needed or not in a unified way (see scale_*_manual)
                pch.legend.title <- .change_if_null(pch.legend.title, as.character(as.list(match.call())['pch']))
                if (is.null(legend.title))
                {
                    legend.title <- ifelse(is(object, 'DA'), yes = 'Y', no = as.character(as.list(match.call())['group']))
                }
                gg_biplot <- gg_biplot + 
                    geom_point(aes(x = variates[, comp[1]], 
                                   y = variates[, comp[2]],
                                   col = group,
                                   shape = pch),
                               fill = fill,
                               alpha = alpha,
                               size = pch.size)
                
                pch_legend <- NULL
                if (isTRUE(pch.legend)) {
                    pch_legend <- guide_legend(title = pch.legend.title, override.aes = list(size = 5))
                }
                # gg_biplot <- gg_biplot + 
                #     scale_shape_manual(values = pch.levels, guide = pch_legend)
            }
            else
            {
                ind.names.repel <- FALSE
            }
            if (!is.null(ind.names))
            {
                if (isTRUE(ind.names.repel)) {
                    gg_biplot <- gg_biplot + 
                        geom_text_repel(mapping = aes(x = variates[, comp[1]],
                                                      y = variates[, comp[2]],
                                                      label = ind.names,
                                                      col = group
                        ), 
                        size = ind.names.size,
                        show.legend = FALSE)
                } else {
                    gg_biplot <- gg_biplot + 
                        geom_text(mapping = aes(x = variates[, comp[1]],
                                                y = variates[, comp[2]],
                                                label = ind.names,
                                                col = group
                        ), 
                        size = ind.names.size,
                        show.legend = FALSE)
                }
                
            }
            col_legend <- NULL
            if (isTRUE(legend)) {
                col_legend <- guide_legend(title = legend.title, override.aes = list(size = 5))
            }
                
            gg_biplot <- gg_biplot + 
                scale_color_manual(values = col.per.group, guide = col_legend)
            
            gg_biplot <-
                gg_biplot +
                theme(
                    legend.text = element_text(size = rel(cex)),
                    legend.title = element_text(size = rel(cex)),
                    axis.title =  element_text(size = rel(cex)),
                    axis.text =  element_text(size = rel(cex))
                )

        }
        
        ## ------------- vars
        
        if (! 'var' %in% hide) 
        {
            loadings <- loadings*scaler
            var.names.col <- .get.ind.colors(group = NULL, 
                                             col = var.names.col,
                                             col.per.group = NULL, 
                                             n_ind = nrow(loadings))
            if (!is.null(var.arrow.col))
            {
                var.arrow.col <- .get.ind.colors(group = NULL, 
                                                 col = var.arrow.col,
                                                 col.per.group = NULL, 
                                                 n_ind = nrow(loadings))
                loadings$var.names.col <- var.names.col
                loadings$var.arrow.col <- var.arrow.col
                ## lines and arrows
                gg_biplot <-
                    gg_biplot + geom_segment(
                        aes(
                            x = 0,
                            y = 0,
                            xend = loadings[,comp[1]],
                            yend = loadings[,comp[2]],
                        ),
                        col = var.arrow.col,
                        arrow = arrow(length = unit(var.arrow.length, "cm")),
                        linewidth = var.arrow.size,
                        show.legend = FALSE
                    )
            }
            
            ## labels
            var.labels <- .get.character.vector(arg = var.names, vec = rownames(loadings))
            ## label angles
            angle <- rep(0, nrow(loadings))
            
            if (!is.null(var.names)) 
            {
                angle <- rep(0, nrow(loadings))
                if (var.names.angle == TRUE)
                {
                    angle <- atan(loadings[, comp[2]]/loadings[, comp[1]]) * 360/(2 * pi)
                }
                
                gg_biplot <-
                    gg_biplot + geom_text_repel(
                        aes(
                            x = loadings[, comp[1]],
                            y = loadings[, comp[2]],
                            label = var.labels,
                            angle = angle,
                            hjust = ifelse(loadings[, comp[1]] > 0, 1, 0),
                            vjust = ifelse(loadings[, comp[2]] > 0, 1, 0)
                        ),
                        col = var.names.col,
                        size = var.names.size,
                        box.padding = 0.1,
                        point.padding = 0.1
                    )
            } 
            
            ## second set of axes
            gg_biplot <- gg_biplot + scale_y_continuous(sec.axis = sec_axis(~.*1/scaler)) +
                scale_x_continuous(sec.axis = sec_axis(~.*1/scaler)) 
        }
        gg_biplot
    }

#' biplot methods for \code{pca} family
#'
#' @inheritParams plotIndiv
#' @inheritParams plotVar
#' @param x An object of class 'pca'or mixOmics '(s)pls'.
#' @param ind.names.repel Logical, whether to repel away label names.
#' @param group Factor indicating the group membership for each sample.
#' @param block Character, name of the block to show for \code{pls} object.
#'   Default to \code{'X'}.
#' @param ind.names.size Numeric, sample name size.
#' @param ind.names.col Character, sample name colour.
#' @template arg/pch.size
#' @param pch A single character or numeric value, or a factor. If a factor, the
#'   levels of the factor are used to define the point types. If a character or
#'   numeric value, the same point type is used for all points. If \code{NULL},
#'   the default point type is used. See examples. 
#' @param var.names Logical indicating whether to show variable names. 
#' Alternatively, a character.
#' @param var.names.col Character, variable name colour.
#' @param var.names.size Numeric, variable name size.
#' @param var.names.angle Logical, whether to align variable names to arrow
#'   directions.
#' @param var.arrow.col Character, variable arrow colour. If 'NULL', no arrows
#'   are shown.
#' @param var.arrow.size Numeric, variable arrow head size.
#' @param var.arrow.length Numeric, length of the arrow head in 'cm'.
#' @param ind.legend.title Character, title of the legend.
#' @param vline Logical, whether to draw the vertical neutral line.
#' @param hline Logical, whether to draw the horizontal neutral line.
#' @param legend Logical, whether to show the legend if \code{group != NULL}.
#' @param legend.title Character, the legend title if \code{group != NULL}.
#' @param pch.legend Character, the legend title if \code{pch} is a factor.
#' @param pch.legend.title Character, the legend title if \code{pch} is a factor.
#' @param cex Numeric scalar indicating the desired magnification of plot texts.
#'   \code{\link[ggplot2]{theme}} function may be used with the output object if
#'   further customisation is required.
#' @param ... Not currently used.
#' @details 
#' \code{biplot} unifies the reduced representation of both the
#' observations/samples and variables of a matrix of multivariate data on the
#' same plot. Essentially, in the reduced space the samples are shown as
#' points/names and the contributions of features to each dimension are shown as
#' directed arrows or vectors.
#' For \code{pls} objects it is possible to use either \code{'X'} or \code{'Y'}
#' latent space using \code{block} argument.
#' @return A ggplot object.
#' @author Al J Abadi
#' @importFrom ggrepel geom_text_repel
#' @example ./examples/biplot-examples.R

#' @method biplot pca
#' @rdname biplot
#' @export
biplot.pca <- .biplot

#' @method biplot mixo_pls
#' @rdname biplot
#' @export
biplot.mixo_pls <- .biplot

#' @method biplot mixo_spls
#' @noRd
#' @export
biplot.mixo_spls <- .biplot
